Operational amplifier for outputting high voltage output signal

An inverting amplifier circuit comprising a high-output voltage operational amplifier of a type in which a low voltage input signal is entered and a high voltage is obtained as output, wherein said operational amplifier comprises:

• a differential amplifier circuit receiving the low voltage input signal;
• and
• a current mirror circuit provided on a downstream side stage of said differential amplifier circuit and driven with a high power supply voltage;
• said differential amplifier circuit including:
• a low withstand voltage differential transistor pair for receiving the low voltage input signal;
• a low withstand voltage constant current source transistor connected to said differential transistor pair;
• and
• a high withstand voltage transistor pair connected between said differential transistor pair and said current mirror circuit, said high withstand voltage transistor pair including transistors respectively connected to transistors of said differential transistor pair;
• said current mirror circuit of the downstream side stage being formed by high withstand voltage transistors, said transistors of said high withstand voltage transistor pair having a gate electrode connected in common to an input terminal supplied with a bias voltage of a low power supply voltage lower than the high power supply voltage;
• first and second capacitances being connected in series with each other between an input end of the low voltage input signal and an output end of said operational amplifier, so as to give an amplification factor substantially equal to unity or more;
• said operational amplifier having an inverting input connected to a junction point of said first and second capacitances.

An inverting amplifier circuit comprising a high-output voltage operational amplifier of a type in which a low voltage input signal is entered and a high voltage is obtained as output, wherein said operational amplifier comprises:

• a differential amplifier circuit receiving the low voltage input signal;
• and
• a current mirror circuit provided on a downstream side stage of said differential amplifier circuit and driven with a high power supply voltage;
• said differential amplifier circuit including:
• a low withstand voltage differential transistor pair for receiving the low voltage input signal;
• a low withstand voltage constant current source transistor connected to said differential transistor pair;
• and
• a high withstand voltage transistor pair connected between said differential transistor pair and said current mirror circuit, said high withstand voltage transistor pair including transistors respectively connected to transistors of said differential transistor pair;
• said current mirror circuit of the downstream side stage being formed by high withstand voltage transistors, said transistors of said high withstand voltage transistor pair having a gate electrode connected in common to an input terminal supplied with a bias voltage of a low power supply voltage lower than the high power supply voltage;
• first and second resistances being connected in series with each other between an input end of the low voltage input signal and an output end of said operational amplifier, so as to give an amplification factor substantially equal to unity or more;
• said operational amplifier having an inverting input connected to a junction point of said first and second resistances.